1. Field of the Invention
The present invention generally relates to a device for providing linear translation of one platform relative to a second platform. More particularly, the invention relates to a device for the lifting and lowering of people in wheelchairs to allow entry into and egress from a vehicle.
2. Description of Related Art
Physically disabled individuals using a wheelchair rely on many different types of mechanical devices to perform routine tasks. For example, a powered lift is often required in order to move such an individual to and from the interior of a vehicle. Conventional wheelchair lifts require extensive modifications to a vehicle in order to attach the lift device to the vehicle. Some of these modifications cause normal vehicle entry and exit to be blocked while the wheelchair lift is in use.
There is a public need for a low profile and low pressure actuated wheelchair lift that does not require extensive vehicle modifications or block vehicle doors. Ideally a wheelchair lift should have a footprint just larger than that which is required to encompass the footprint created by the wheelchair. Most power devices for actuating a lift mechanism requires the use of high pressure piston driven devices or heavy electrical motors and gear boxes with commensurate heavy articulating structural members.
It is an object of this invention to provide a lightweight lift mechanism requiring very low pressures for the actuation and lifting force.
It is a further object of the invention to provide a constant translation or lifting force for a given low pressure input fluid.
It is still further object of the invention to provide a lift that travels a straight line path between the lift platform and the bottom platform and has a high aspect ratio (greater than 3 to 1) between the stowed height of the device and the deployed height of the device.
U.S. Pat. No. 3,843,092 and U.S. Pat. No. 3,730,366, for example, disclose lifting structures that could be used to lift a wheelchair. However, these and other conventional lifting structures have some disadvantages and limitations, namely their large footprint and cost. Most lift mechanisms require high pressure actuators and/or heavy electric motors and gear boxes in order to affect the operation of the lift. The mechanism members are necessarily high strength and heavy in order to withstand these high pressures and associated forces. Thus, the weight of the finished product is also relatively heavy.
In light of the foregoing, there is a need in the art for a lightweight, low profile, low pressure actuated improved lift or translation device.
Accordingly, the present invention is directed to a device that substantially obviates one or more limitations of the related art. To achieve these and other advantages, and in accordance with the purposes of the invention, as embodied and broadly described herein, the invention includes a linear translation device having a base, a platform above the base, an intermediate platform between the base and the platform, an inflatable bladder between the base and the platform for lifting the platform as the bladder is pressurized, at least one first hinge member and at least one second hinge member. Another aspect of the invention includes a hinged bracket assembly formed of two members.
In an aspect of the invention, the first hinge member has a first end pivotally connected to the base and a second end pivotally connected to the intermediate platform. In addition, the second hinge member has a first end pivotally connected to the platform and a second end pivotally connected to the intermediate platform.
In another aspect of the invention, the hinged bracket assembly comprises a first bracket member pivotally connected to the base at one end and pivotally connected to a second bracket member at the other end. The other end of the second bracket member is pivotally connected to the platform. The pivotal connection between the two bracket members is formed along a hinge axis in a plane substantially perpendicular to hinge axes of the pivotal connections of the first and second hinge members. The bracket hinge axis is in the same plane as the intermediate platform. The intermediate platform has two concave cutouts to provide clearance for the first and second bracket members as they fold inward toward each other during deflation of the inflatable bladder.
In yet another aspect, the lift device includes a second platform, and a second inflatable bladder for moving the second platform away from the platform during inflation of the second inflatable bladder. In one preferred configuration having brackets and hinged members, vertical motion is imparted to the second platform without substantial translation of the second platform. In another preferred configuration having hinge members, the second platform simultaneously translates and elevates.
In still another aspect, the lift device includes a hose for fluid coupling an exhaust system of a vehicle, or similar source of pressurized air, to an interior of the inflatable bladder so that exhaust of the vehicle inflates the bladder.
Additional features, advantages, and objectives of the invention will be set forth in the description that follows, and in part, will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the written description and claims herein as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the invention as claimed.